This invention relates to mechanisms for preventing a second staple from being fed from a staple magazine into a mechanism for driving the staples until a staple already in the mechanism is ejected.
Many staplers are known of the type comprising a housing having a passageway extending from an inlet opening to an outlet opening, with the passageway being adapted to guide a single staple moved from the inlet to the outlet opening; means for biasing a stack of staples into the inlet opening from a staple magazine; a ram slidably mounted on the housing for movement between a load position spaced from the inlet opening to afford movement of one of the staples into the passageway, along the passageway with an end portion of the ram pushing a staple in the passageway to an eject position at which the staple is expelled from the outlet opening; and a drive mechanism which is often manually activatable for propelling the ram from its load to its eject position in opposition to a biasing means. Typically portions of the ram cover the inlet opening to prevent another staple from being fed into the passageway as the ram moves a staple in the channel toward the outlet opening. If the drive means is not completely activated to cause the ram to eject the staple from the outlet opening, however, the ram will return to its load position under the influence of the biasing means, a second staple will enter the passageway, and upon subsequent activation of the drive mechanism the two staples in the passageway will jam the stapler.
While many prior art devices have been devised to prevent such double feeding, most are not as simple, inexpensive, or reliable as is desired.